- previous support for file appending (largely unused) always
specified opening with the std::ios_base::app flag.
Now differentiate between append behaviours:
APPEND_APP
~~~~~~~~~~
Corresponds to std::ios_base::app behaviour:
- Existing files will be preserved and a seek-to-end is performed at
every write. With this mode seeks/repositioning within the file
will effectively be ignored on output.
APPEND_ATE
~~~~~~~~~~
Largely approximates std::ios_base::ate behaviour:
- Existing files will be preserved and a seek-to-end is performed
immediately after opening, but not subsequently. Can use seekp()
to overwrite parts of a file.
